Please accept this in the good nature with which I offer it, and don't flame me (again).
But, the only two programs that I can remember, just off hand, that totally rendered my PC unbootable and
forced me to do a Ghost restore to get my computer back, were CCleaner and Defraggler.
I don't want either of those programs anywhere Near my PC.
Windows Disk Cleanup, when run in the extended mode does a great job of cleaning out system garbage
and the Windows Defrag does a good job of Defragmenting the HD.
Also, stay away from Auslogic's Defrag program. I tried it and it made an unHoly mess of my HD.
I had to do a Backup and Restore with Ghost, to reorder my HD. Once bitten, twice shy!
Cheers mates!
OT